Genetically engineering cell-derived exosomes with anti-CD3 and anti-HER2 antibodies (aCD3-aHER2 SMART-Exos) dually target T cells and HER2+ breast cancer, selectively inducing HER2-expressing tumor-specific immunity and activating cytotoxic T cells toward attacking breast cancer cells (107). The gene discussed is ERBB2; the disease is breast cancer.